opiates and opioids Flashcards
what is an opiate?
natural narcotic opioid found in the opium poppy (papaver somniferum)
what is an opioid?
any natural or synthetic compound or endogenous peptides that exert biological effects at the opioid receptor
what are the 3 major psychoactive opiates
major- morphine, codeine, thebaine
what are the three pharmacological use of natural opiates and which one is known to be the most potent and effective pain reliever
analgesic, antitussive, and decreased gastric motility
analgesic
what does antitussive and decreased gastric motility do
antitussive-> cough suppressant, in which codeine has decreased the analgesic effect but retains antitussive effects
decreased gastric motility-> can be used to treat diarrhea esp pathogenic
-> Loperamide is an opioid derivative that does not penetrate the BBB and is used to treat diarrhea
what is an example of semi-synthetic opioid, what was the trade name that it was under and what was it used for
diacetylmorphine
heroin
cough suppressant, analgesic, and cure for morphine addiction
what are the administration routes for natural opiates
oral- morphine readily absorbed through GI but high variability, codeine has more consistent oral absorption
Subcutaneous, IM, IV- more stable systematic levels and IM is the preferred routes for morphine in clinical setting and IV is common for recreational use
inhalation- historic route of (recreational) administration for raw opium is smoking
what are the administration routes for semi-synthetic opioid?
oral- heroin administration by oral route produces the same potency and efficacy as morphine
IV- dramatically more potent and rapid than morphine due to increased lipophilic structure (increased BBB permeability)
inhalation or intranasal-> occasional route for recreational use
Fill in the blank: Development of numerous semi-synthetic opioids followed the isolation of ________ and _______ and subsequent discovery of the structures
morphine and codeine
TRUE OR FALSE: freebase heroin can be smoked while other preparations can be finely ground and snorted
true
at what doses do opioids exert limited psychoactive effects
5-10mg morphine
what are 5 therapeutic effects of opioids?
pain relief, drowsiness, constriction of pupils, decreased sensitivity to external or internal stimuli, dream-filled sleep
for more, look at slide 10
what are two subjective effects of high doses of opioids
-euphoria or elation ( in contrast to relaxed state at lower doses)
- rush-> most pronounced by IV (rapid, intense state of euphoria, described by others as a “whole body orgasm”)
what are three physiological effects of high doses?
pinprick pupils, nausea and vomiting ( opioids can act at the chemoreceptor trigger zone in the area postrema to induce the vomit reflex) and moderate respiratory depression
Fill in the blank: Prescription opioids (________) are one of the fastest growing classes of drugs of abuse
oxycontin
TRUE OR FALSE: tolerance to opioids develops slowly and tolerance to respiratory and euphoric effects develops more slowly than tolerance to analgesic effects
false: quickly and rapidly
what are the 3 types of tolerance?
metabolic-> some increase in drug metabolism
behavioural-> highly relevant in addicts
pharmacodynamic-> principle mechanism of tolerance– decreased expression of opioid receptors
what is the reason why there are somewhat exaggerated perceptions of opioid withdrawal
cinematic creative license
True or false: opioid withdrawals are much more severe than withdrawal from barbiturates or alcohol
false; much less severe, since severe alcohol withdrawal can be fatal
opioids never fatal
what two things is withdrawal heavily influenced by
drug tolerance and dependence (check slide 15 for extra information and graph)
what is rebound hyperactivity?
withdrawal produces neurochemical and behavioural changes that are often opposite to the effects of intoxication
when do stages of withdrawal begin
6-12 hours after last administration, peaks 26-27hours persists less than 1 week
what can be seen in the first stage of withdrawal
- Restlessness and agitation is first sign
- Excess yawning, agitation, violence
- Chills, hot flashes, shortness of breath
- Intense piloerection (goosebumps) – origin of the term ‘cold turkey’
- Increasing drowsiness and deep sleep (often 8-12 hours)
what can be seen in the second stage of withdrawal
- Cramps in stomach, back, legs
- Vomiting, diarrhea, profuse sweating
- Twitching of the extremities – shaking of hands and kicking of legs – origin of the term ‘kicking the habit’
- Symptoms become progressively less severe until gradually disappearing
what is withdrawal symptoms reduced by and what stop withdrawal immediately
- reduced by alcohol
- stopped immediately by opioid administration which is induced by opioid antagonists
what kind of administration of high doses cause death
IV heroin or morphine
what are some of the results from high doses of opioids (overdose)
- Comatose state, pinpoint pupils, and severe respiratory depression
- Lowers seizure threshold – convulsions common
- Death occurs by severe respiratory depression or combination of supressed cough reflex, unconsciousness, and vomiting
- Contaminants such as quinine (used to cut heroin) are a probable cause of many overdoses – causes frothing from mouth and nose and death by pulmonary edema
what is opioid overdose affected by
behavioural tolerance- drug use outside conditioned environment can lead to increased drug effects
what can be used to treat an overdose
opioid antagonists (naloxone)
what is a major side effect of clinical opioid use which does not develop tolerance?
constipation
what are two other chronic effects of opioid use
- Hormone imbalance
->Hypogonadism in majority of chronic opioid
users (up to 90%)
->Amenorrhea by supressing luteinizing
hormone - Opioid-induced hyperalgesia (remember this, it is the most important one)
->Chronic opioid use alters the homeostasis
of pain signalling pathways
->With time pain thresholds decrease resulting
in increased sensitivity to pain – often
mistaken for tolerance resulting in increased
dosage
what are two ways to manage addictions
maintenance therapies- the real harm of opioid abuse is caused by illegality and expense of the drug
british system- provides heroin prescription to addicts at public expense
why is there a large amount of adverse health effects of opioid abuse
due to the impurities in drug and spread of diseases (HIV, hepatitis) due to unsafe administration
what is methadone maintenance (the US system)
- Synthetic opioid administered orally
- Decreased euphoric effects
- Effects last ~24 hours in preventing withdrawal symptoms
- Competitive for receptor sites with morphine (blocks euphoric effects of heroin if co-administered)
- Reduces associated morbidity and mortality
- 80-90 % relapse rates
True or false: methadone has increased potency and increased effects and only has a short duration of effect
false; decrease, decrease, longer duration of effect
true or false: methadone withdrawal is much less severe than heroin
true
what is LAMM
- Orally administrable maintenance drug
- Comparable to methadone therapy but longer lasting – up to 72 hours (administration required only 3x per week)
- Some risk of life-threatening ventricular rhythm disorders (not widely used)
what is buprenorphine
- Analgesic, mixed agonist-antagonist at different opioid receptors
- Similar to methadone, but fewer adverse effects (no respiratory depression)
- Is itself addictive, but thought to be easier to kick than heroin
- Investigational use in neonatal abstinence – infants born to opioid addicted mothers
- Suboxone is currently favoured in Canada – buprenorphine and naloxone
